This is not a foolish question, it is a brilliant question, but at the same time we must know that there is no human formula to enter the kingdom of heaven, but all this is about grace, an undeserved gift that God gives us through the death of His Son on the cross of Calvary.
But if we talk about entering the kingdom of heaven there is something that is proper to each believer: “Born again”. We can not say that we are Christians if we are not born again, this is the distinguishing mark of each one of us and our beloved Lord Jesus Christ spoke about the new birth:
3 Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God.
4 Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother’s womb, and be born?
5 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.